Some of the smaller alluvial works are in seasonally dry creek /...

Some of the smaller alluvial works are in seasonally dry creek / river beds and just use an excavator and truck to a nearby semi portable gravity plant (still producing +70% tin in concentrate).
Minimal environmental impact as the plant spoil is simply returned to the creek bed from whence it came.
All in all a low capex, low opex, high margin revenue stream employing 3 -5 staff that could run autonomously from the main plant at Mt. Garnet on a seasonal basis.

Here is one example plant (that is for sale 30Klm from Mt. Garnet)
http://www.bookallmine.com/tinmineinformation.htm